Planks are one of the hardest moves out there. They involve not only your abs but also your lower back, glutes, hamstrings, shoulders, chest and upper back. All of these muscles have to work together to execute a perfect plank, here are some dos and don'ts that help you hit that level of perfection. DON'T let your hips sag. Doing so takes your abs out of the equation and puts the pressure on your arms and toes to support you. It is also a risk to your lower back. Your ideal body position is head, hips and heels in line, back straight, head neutral. DON'T let your butt lift into the air. Again, your abs will be doing nothing to support your weight in this position. DO press through the heels of your hands and spread your shoulder blades apart. Allowing your shoulders to hunch inward puts strain on your neck and shoulder girdle, making it difficult to maintain proper form. DON'T let your head hang. This pulls your spine out of alignment and overstretches the muscles in the back of your neck and shoulders. Look a few inches in front of your hands to lift your head to a stable, neutral position. DO press your heels toward the wall behind you and squeeze your glutes. This tightens our posterior chain and helps support your hips and lower back by removing pressure from your abs. DO focus on your breathing. Inhale through your nose for a two count then exhale through your mouth for a four count. This oxygenates your muscles and helps you pass the time. DON'T hold your plank too long. If you can't hold the proper form the whole time, you're going to strain your muscles. If you are new to working out, aim for 20 seconds of work followed by 20 seconds of rest. As you progress, up it to 30 seconds of work/rest, then 45 then 60. Eventually you'll be holding 2 minutes like a champ. DO try different plank variations as you get stronger to train your core in different ways. Try side planks, forearm planks, knee-in planks and even walking planks.